Fuel injection devices for the operation of an internal combustion engine have been widely known for many years. In the case of a so-called common-rail injection system, the feeding of fuel into the respective combustion chamber of the internal combustion engine takes place by means of injectors, in particular by means of piezo injectors. As a rule, injectors are controlled here from within a control unit via an electrical circuit (final stage), and regulated by a software program. The electrical circuit arrangement and the microprocessor on which the software runs, are here as a rule components of the control unit, in particular of an engine control unit. Faults can arise during operation of the internal combustion engine, such as for example a short circuit of a connecting line of an injector to electrical ground or the battery, which call for the fastest possible separation of the electrical circuit arrangement from the injectors, in order to protect these against thermal destruction.
According to the prior art, methods are known, in which by means of additional components on the control unit it is attempted to determine the fault location within the fuel injection system with the maximum possible precision.